
DocID024597 Rev 5
RM0351
USB on-the-go full-speed (OTG_FS)
1774
47.15.21 OTG Host frame interval register (OTG_HFIR)
Address offset: 0x404
Reset value: 0x0000 EA60
This register stores the frame interval information for the current speed to which the
OTG_FS controller has enumerated.
Bits 31:3 Reserved, must be kept at reset value.
Bit 2
FSLSS:
FS- and LS-only support
The application uses this bit to control the core’s enumeration speed. Using this bit, the
application can make the core enumerate as an FS host, even if the connected device
supports HS traffic. Do not make changes to this field after initial programming.
1: FS/LS-only, even if the connected device can support HS (read-only)
Bits 1:0
FSLSPCS:
FS/LS PHY clock select
When the core is in FS host mode
01: PHY clock is running at 48 MHz
Others: Reserved
When the core is in LS host mode
00: Reserved
01: Select 48 MHz PHY clock frequency
10: Select 6 MHz PHY clock frequency
11: Reserved
Note: The FSLSPCS must be set on a connection event according to the speed of the
connected device (after changing this bit, a software reset must be performed).
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
Res.
Res.
Res.
Res.
Res.
Res.
Res.
Res.
Res.
Res.
Res.
Res.
Res.
Res.
Res.
RLD
CTRL
rw
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
FRIVL
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw